The electric motors, as well as other components, used in alternative fuel vehicles, such as hybrid and fuel cell vehicles, often utilize alternating current (AC) power supplies. However, the power sources, such as batteries and fuel cells, used in such applications only provide direct current (DC) power. Thus, devices known as power inverters are used to convert the DC power to AC power.
Modern automotive power inverters often utilize power modules (or microelectronic die), which include integrated circuits with multiple semiconductor devices (e.g., transistors and diodes) formed thereon, to convert the DC power to AC power. Due to the high amounts of current used, the power modules generate large amounts of heat. In order to ensure reliable performance, the power inverters also include cooling systems to transfer heat away from the power modules.
Conventional cooling systems used in automotive inverters often include a metal heat sink, or cold plate (i.e., with a coolant flowing therethrough), connected directly to the chassis of the inverter. The power modules are usually mounted to a stack of various substrates and/or a base plate, which is attached to the heat sink. Heat from the power modules is conducted through substrates and/or baseplate into the heat sink, where it is removed from the inverter. The heat sink may also be used to cool other electronic components within the chassis of the inverter, such as busbars, inductors and capacitors.
When the power modules are operated, capacitive coupling between the power modules and the chassis occurs, and electromagnetic interference (EMI) currents are injected into the chassis, which can adversely affect the performance of the inverter and the motor. Thus, “Y-caps,” or Y-capacitors, are often installed at the DC power inputs to the inverter to reduce the effects of the capacitive coupling and the EMI currents, thus increasing the costs of manufacturing.
Accordingly, it is desirable to provide an inverter assembly with a reduced capacitance between the chassis and the power modules. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.